Electrophoretic device, electrophoretic display, and electronic apparatus

ABSTRACT

An electrophoretic device includes an electro-optical panel including an electrophoretic layer having an electrophoretic dispersion containing electrophoretic particles dispersed in a liquid-phase disperse medium, wherein the electro-optical panel is enclosed with a single protective film folded, and a first portion of the protective film is bonded to a second portion of the protective film at a first bonding portion.

BACKGROUND

1. Technical Field

Several aspects of the present invention relate to an electrophoreticdevice, an electrophoretic display, and an electronic apparatus.

2. Related Art

Electrophoretic displays including an electrophoretic dispersioncontaining a liquid-phase dispersion medium and electrophoreticparticles have been known, electrophoretic displays employing the factthat applying an electric field changes the distribution state of theelectrophoretic particles to change optical properties of theelectrophoretic dispersion.

Electrophoretic displays do not require backlights, thus reducing costsand thicknesses. Furthermore, electrophoretic displays havedisplay-memory characteristics in addition to wide viewing angles andhigh contrast and thus have been receiving attention as thenext-generation display device.

Electrophoretic displays each having a structure in which microcapsulescontaining an electrophoretic dispersion are disposed between atransparent substrate having a common electrode (transparent electrode)and a substrate having a driving electrode formed of a segment electrodehave been known.

Microencapsulation of the electrophoretic dispersion can advantageouslyprevent a drain of the dispersion in production processes ofelectrophoretic displays and suppress precipitation and aggregation ofelectrophoretic particles. These substrates are composed of, forexample, plastic in view of flexibility, non-fragility, a reduction inweight, and the like.

In recent years, microencapsulation of a disperse system in advance hasbeen widely employed.

For example, JP-A-64-86116 discloses an electrophoretic display in whichmicrocapsules containing a dispersion system are disposed between a pairof electrodes opposite each other, at least one of the pair of theelectrodes being transparent.

JP-A-10-149118 discloses an electrophoretic display including alight-transmitting transparent substrate, an opaque back substrateopposite the transparent substrate, transparent electrodes disposed onopposed faces of the substrates, and many microcapsules disposed in anenclosed region between the transparent electrodes.

In this way, microencapsulation of a disperse system facilitatesdisperse-system-enclosing treatment and achieves a satisfactory displayimage.

In the case where plastic substrates are used in electrophoreticdisplays, plastic substrates allow water in air to permeatetherethrough, thus providing insufficient blockage of water and thelike. As a result, water permeating the plastic substrates enters thedisplay to degrade the microcapsules. The degradation of themicrocapsules disadvantageously reduces the lifetime of theelectrophoretic displays.

To solve the problems, a method for laminating a protective film aroundan electrophoretic display (hereinafter, referred to as a “display”) toseal the display with the protective film has been widely employed.

For example, as shown in FIG. 8, a display 64 is disposed between a pairof protective films 60 and 60. The protective films 60 and 60 are bondedat the periphery of the display 64 to form a seal 65, thereby sealingthe entire display 64 with the protective films 60 and 60. As shown inthe figure, it is necessary to use an adhesive 66 to bond the protectivefilms 60 and 60.

SUMMARY

An advantage of some aspects of the invention is that an electrophoreticdisplay which prevents the penetration of water and the like in air tohave more satisfactory moisture resistance and an electronic apparatusare provided.

An electrophoretic device according to the invention includes anelectro-optical panel including an electrophoretic layer having anelectrophoretic dispersion containing electrophoretic particlesdispersed in a liquid-phase disperse medium, wherein the electro-opticalpanel is enclosed with a single protective film folded, and a firstportion of the protective film is bonded to a second portion of theprotective film at a first bonding portion.

In the above-described electrophoretic device, the electro-optical panelis preferably enclosed so as to be disposed between the first bondingportion and a third portion of the protective film.

In the above-described electrophoretic device, preferably, a mainsurface of the electro-optical panel is enclosed so as to be disposedbetween the first bonding portion a third portion of the protectivefilm, and the main surface of the electro-optical panel is covered withthe third portion.

In the above-described electrophoretic device, in the case where themain surface of the electro-optical panel is used as a display portionor the like, a seamless portion of the protective film can be used asthe third portion, thus improving visual identification. The seamlessportion can be used as the third portion, thus reducing the effect ofdegradation factors, such as air and water, to the main surface.

In the above-described electrophoretic device, a fourth portion of theprotective film may be bonded to a fifth portion of the protective filmat a second bonding portion, and the electro-optical panel may beenclosed in such a manner that the first bonding portion is opposite thesecond bonding portion with the electro-optical panel providedtherebetween.

In the case where the electro-optical panel is in the form of arectangle, preferably, the rectangle has a first short side; a secondshort side opposite the first short side; a first long side intersectingwith the first short side and the second short side and being longerthan the first short side and the second short side; and a second longside intersecting with the first short side and the second short sideand being opposite the first long side, both of the first portion andthe second portion protrude outward from the first short side of theelectro-optical panel, and both of the fourth portion and the fifthportion protrude outward from the second short side.

Alternatively, in the case where the electro-optical panel is in theform of a rectangle, preferably, the rectangle has a first short side; asecond short side opposite the first short side; a first long sideintersecting with the first short side and the second short side andbeing longer than the first short side and the second short side; and asecond long side intersecting with the first short side and the secondshort side and being opposite the first long side, both of the firstportion and the second portion protrude outward from the first shortside of the electro-optical panel, and both of the fourth portion andthe fifth portion protrude outward from the second short side.

In the above-described electrophoretic device, in the case where theelectro-optical panel is in the form of a rectangle, preferably, therectangle has a first short side; a second short side opposite the firstshort side; a first long side intersecting with the first short side andthe second short side and being longer than the first short side and thesecond short side; and a second long side intersecting with the firstshort side and the second short side and being opposite the first longside, and the electro-optical panel includes a driving circuit disposedalong at least one of the first long side and the second long side.

Preferably, the above-described electro-optical panel includes aplurality of terminals for electrically connecting the electro-opticalpanel and the outside of the electro-optical panel, and the plurality ofthe terminals are disposed along at least one of the first short sideand the second short side.

To overcome the problems, an electrophoretic display includes a displayportion including an electrophoretic layer having an electrophoreticdispersion containing electrophoretic particles dispersed in aliquid-phase disperse medium, the electrophoretic layer being disposedbetween a pair of substrates, wherein the display portion is enclosedwith a single protective film folded, and ends of the protective film inthe folding direction are overlapped and fixed at one of the front sideand the back side of the display portion to form a seal.

The seal is preferably disposed at the back side of the display portion.

Preferably, the display portion is in the form of a rectangle, thefolding direction of the protective film corresponds to the direction ofthe short side of the display portion, and the seal is thus disposedalong the direction of the long side of the display portion.

According to the invention, the display portion preferably includes adriving circuit disposed along at least one of the first long side andthe second long side.

Preferably, the display portion includes a plurality of terminals forelectrically connecting the display portion to the outside of thedisplay portion, and the plurality of the terminals are disposed alongat least one of the first short side and the second short side.

The overlap width of the ends in the folding direction at the sealpreferably ranges from half the length of the short side to the lengthof the short side of the display portion.

To overcome the problems, the invention provides an electrophoreticdisplay including a display unit having an electrophoretic layerdisposed between a pair of substrates, the electrophoretic layerprovided with an electrophoretic dispersion containing electrophoreticparticles dispersed in a liquid-phase disperse medium, and the displayunit being sealed with a protective film. The display unit is enclosedwith the single protective film folded. Ends of the protective film inthe folding direction are overlapped and fixed at one of the front sideand the back side of the display unit with an adhesive to form a foldedseal.

According to the invention, the display unit is enclosed with the singleprotective film, and the ends are overlapped and fixed at one of thefront side and the back side of the display unit, thus reducing thesealing region that may undergo the penetration of water and the like.This reduces the number of paths for the penetration of water and thelike, thus enhancing sealing properties and improving moistureresistance. Furthermore, according to the invention, the folded seal isdisposed at one of the front side and the back side, thus eliminatingseals disposed at both sides of the display unit in the foldingdirection. As a result, the protrusion of seals all around the displayunit is eliminated, thus resulting in the miniaturization of the displayunit. Furthermore, the overlap width of the folded seal such that thepenetration of water and the like can be sufficiently inhibited can beensured, thus improving sealing properties. The penetration of water canbe inhibited with high reliability, thus preventing the degradation ofthe microcapsules in the display unit and imparting satisfactorymoisture resistance to the display unit. This can prevent a degradationin display performance and markedly improve the durability and life timeof the display unit, thus maintaining satisfactory display performanceover long periods of time.

In the electrophoretic display of the invention, the folded seal ispreferably disposed at the back side of the display unit.

According to the structure, the folded seal is disposed at the back sideof the display unit. For example, the front side of the display unitfunctions as a display surface where a viewer visually identifies animage, thus providing a satisfactory image for the viewer. Hence, theviewer can visually identify a clear image with comfortable feeling.Moreover, the folded seal is disposed at the backside of the displayunit; hence, the aesthetics of the product is not degraded.

According to the electrophoretic display of the invention, in the casewhere the display unit has a rectangular shape, preferably, the foldingdirection of the protective film corresponds to the direction of theshort side of the display unit, thus forming the folded seal along thelong side of the display unit.

In general, in the case where an electrophoretic display is in the formof a rectangle when viewed in plan, a driving-circuit substrate(driving-circuit portion) is disposed at one side in the direction ofthe long side of the rectangle. According to this structure, the foldedseal is disposed along the long side of the rectangular display unit toform a known sealing structure at both sides in the direction of thelong side. Thus, the driving-circuit substrate and the like can also beconnected as in the known art.

Furthermore, in the electrophoretic display of the invention, the foldedseal has an overlap width ranging from half the length of the short sideto the length of the short side of the display unit.

According to the structure, the overlap width is designed to range fromhalf the length of the short side to the length of the short side, thussufficiently inhibiting the penetration of water and the like. Hence,the moisture resistance at the folded seal is further improved, and thedegradation in display performance due to the penetration of water andthe like can be prevented. Thereby, the reliability as the product canbe ensured.

An electronic apparatus of the invention includes any of theelectrophoretic display.

This structure includes the electrophoretic display which hassatisfactory moisture resistance and prevents the penetration of waterand the like in air into the display unit. Thus, a high-quality,high-reliability electronic apparatus can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a schematic cross-sectional view showing a structure of anelectrophoretic display according to the embodiment.

FIG. 2 is a schematic plan view showing a structure of theelectrophoretic display according to the embodiment.

FIG. 3 is a cross-sectional view illustrating a step of enclosing adisplay unit with a protective film.

FIG. 4 is a cross-sectional view illustrating a step of enclosing adisplay unit with a protective film using a vacuum laminator.

FIG. 5 is a perspective view of the appearance of a wrist watch.

FIG. 6 is a perspective view of the appearance of a mobile phone.

FIG. 7 is a perspective view of the appearance of electronic paper.

FIG. 8 is a schematic cross-sectional view showing a structure of aknown electrophoretic display.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The invention will be described in detail below.

FIG. 1 shows an embodiment of an electrophoretic display 1 of theinvention. In FIG. 1, reference numeral 1 represents an electrophoreticdisplay. The electrophoretic display 1 includes a display unit 4 havinga rectangular shape when viewed in plan; and a single protective film 5with which the entire display unit 4 is enclosed. The display unit 4includes a first substrate 2 having a segment electrode 6 (drivingelectrode); a second substrate 3 having a common electrode 7, the secondsubstrate 3 being opposite the first substrate 2; and an electrophoreticlayer 13 held by the substrates 2 and 3. The electrophoretic layer 13has many microcapsules 10 each including an electrophoretic dispersion11 containing a liquid-phase dispersion medium 9 and electrophoreticparticles 8. The electrophoretic display 1 displays an image by applyingan electric field to the electrophoretic dispersion 11 to change thedistribution state of the electrophoretic particles 8.

Layers and components are shown at different scales so as to berecognizable in FIG. 1.

In particular, in the case where the electrophoretic display 1 needs tohave flexibility like an IC card or electronic paper, film or sheetsubstrates each composed of a resin may be used as the first substrate 2and the second substrate 3. On the other hand, in the case where theelectrophoretic display 1 does not need to have flexibility like generalpanels, substrates each composed of glass, a hard resin, or asemiconductor material such as silicon may be used.

In this embodiment, the second substrate 3 side functions as a displaysurface seen by a user. Thus, the second substrate 3 disposed at theuser side of the electrophoretic display 1 is composed of a transparentmaterial having high transmittance. Examples of the material suitablyused for the resin substrate include polyesters, such as polyethyleneterephthalates (PETs) and polyethylene naphthalates (PENs); polyethersulfones (PESs); polycarbonates (PC); and polyethylenes (PE).

The common electrode 7 is formed by evaporation or the like on theentire inner surface of the second substrate 3. Examples of the commonelectrode 7 usable include conductive oxides such as indium-tin oxides(ITO); electronic conductive polymers such as polyanilines; and ionicconductive polymers each containing an ionic material, such as NaCl,LiClO4, or KCl, dispersed in a matrix resin, such as a polyvinyl alcoholresin or a polycarbonate resin. In this embodiment, an indium-tin oxide(ITO) is used.

On the other hand, the first substrate 2 opposite the second substrate 3does not function as a display surface and thus does not need to havetransparency (high transmittance). A polyimide (PI), a polyvinylchloride (PVC), a polystyrene (PS), a polypropylene (PP), apolycarbonate (PC), a poly(ether ether ketone) (PEEK), a resin such asan acrylic or a polyacrylate, a liquid-crystal polymer, a metal such asstainless steel, or glass may be used in addition to the materials forthe first substrate 2.

The segment electrode 6 having a predetermined shape is disposed on theinner surface of the first substrate 2. To ensure margins on the firstsubstrate 2, the segment electrode 6 is formed in such a manner thatgaps are formed between the segment electrode 6 and the periphery of thefirst substrate 2. The face (inner face) of the substrate having thegaps has step height due to the segment electrode 6. Examples of thematerial usable for the segment electrode 6 include conductive oxidessuch as indium-tin oxides (ITO); electronic conductive polymers such aspolyanilines; and ionic conductive polymers each containing an ionicmaterial, such as NaCl, LiClO4, or KCl, dispersed in a matrix resin,such as a polyvinyl alcohol resin or a polycarbonate resin; metals, suchas aluminum, copper, gold, silver, platinum, nickel, and tin. In thisembodiment, the segment electrode 6 is formed by a copper foil pattern.

The electrophoretic layer 13 disposed between the first substrate 2 andthe second substrate 3 includes the microcapsules 10 densely arranged.As shown in FIG. 1, many microcapsules 10 are arranged at least on thesegment electrode 6 and its periphery. The microcapsules 10 eachcontains the electrophoretic dispersion 11 having the electrophoreticparticles 8 and the liquid-phase dispersion medium 9 for dispersing theparticles therein, as described above. The microcapsules 10 havesubstantially the same diameter. In this embodiment, the microcapsules10 each have a diameter of about 50 μm. To arrange the microcapsules 10within a display region A regulated by the segment electrode 6, themicrocapsules 10 are also arranged outside the display region A toensure the margins described above. The second substrate 3 holding theelectrophoretic layer 13 with the first substrate 2 is bonded along thearrangement of the microcapsules 10 as shown in the figure.

Applying an electric field to the electrophoretic dispersion 11contained in the microcapsules 10 changes the distribution state of theelectrophoretic particles 8 to change optical properties of theelectrophoretic dispersion 11.

Examples of the liquid-phase dispersion medium 9 include a combinationof a surfactant and the like with one or a mixture selected from water;alcohol solvents, such as methanol, ethanol, isopropanol, butanol,octanol, and methyl cellosolve; esters, such as ethyl acetate and butylacetate; ketones, such as acetone, methyl ethyl ketone, and methylisobutyl ketone; aliphatic hydrocarbons, such as pentane, hexane, andoctane; alicyclic hydrocarbons, such as cyclohexane andmethylcyclohexane; aromatic hydrocarbons such as long-chain alkylgroup-containing benzenes, e.g. benzene, toluene, xylenes, hexylbenzene,heptylbenzene, octylbenzene, nonylbenzene, decylbenzene, undecylbenzene,dodecylbenzene, tridecylbenzene, and tetradecylbenzene; halogenatedhydrocarbons, such as methylene chloride, chloroform, carbontetrachloride, and 1,2-dichloroethane; carboxylates; and other oils.

The electrophoretic particles 8 are organic or inorganic particles(polymer or colloid) having a property in which the particles move inthe liquid-phase dispersion medium 9 by electrophoresis due to apotential difference.

Examples of the electrophoretic particles 8 include black pigments, suchas aniline black, carbon black, and titanium black; white pigments, suchas titanium dioxide, zinc white, and antimony trioxide; azo pigments,such as monoazo, disazo, and polyazo; yellow pigments, such asisoindolinone, chrome yellow, yellow iron oxide, cadmium yellow, titanyellow, and antimony; azo pigments, such as monoazo, disazo, andpolyazo; red pigments, such as quinacridone red and chrome vermilion;blue pigments, such as phthalocyanine blue, indanthrene blue, ananthraquinone dye, iron blue, ultramarine blue, and cobalt blue; greenpigments such as phthalocyanine green. One or two or more of these maybe used.

According to need, the pigment may further contain a charge controlagent, such as particles composed of an electrolyte, a surfactant,metallic soap, a resin, rubber, an oil, a varnish, or a compound; adispersant, such as a titanium coupling agent, an aluminum couplingagent, or a silane coupling agent; a lubricant; and a stabilizer.

Examples of the material constituting the film of each microcapsule 10include composites of gum arabic and gelatin; and compounds, such asurethane resins, melanin resins, and urea resins.

In the electrophoretic display 1 according to this embodiment, two typesof electrophoretic particles 8 are contained in the microcapsules 10.One is negatively charged. The other is positively charged. Examples ofthe two types of the electrophoretic particles 8 include titaniumdioxide, which is a white pigment, and carbon black, which is a blackpigment. Since such two types, i.e., white and black, of theelectrophoretic particles 8, when a numeral and the like are displayed,for example, the numeral and the like may be displayed with the blackelectrophoretic particles 8. Alternatively, one type of theelectrophoretic particles 8 alone may be used. In this case, a displaymay be performed by electrophoresis of the particles toward the commonelectrode 7 side or the segment electrode 6 side.

In particular, the microcapsules 10 are particularly fixed on apredetermined region on the common electrode 7 on the second substrate 3with a binder 12. A binder having satisfactory affinity for the film ofeach microcapsule 10, excellent adhesion to the common electrode 7, andinsulating properties may be used as the binder 12. Examples of thereofinclude thermoplastic resins, such as polyethylene, chlorinatedpolyethylene, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylatecopolymers, polypropylene, ABS resins, methyl methacrylates resins,vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, vinylchloride-vinylidene chloride copolymers, vinyl chloride acrylatecopolymers, vinyl chloride-methacrylic acid copolymers, vinylchloride-acrylonitrile copolymers, ethylene-vinyl alcohol-vinyl chloridecopolymers, propylene-vinyl chloride copolymers, vinylidene chlorideresins, vinyl acetate resins, polyvinyl alcohol, polyvinyl formal, andcellulose resins; polymers, such as polyamide resins, polyacetal,polycarbonate, polyethylene terephthalate, polybutylene terephthalate,polyphenylene oxide, polysulfone, polyamide-imide,polyaminobismaleimide, polyether sulfone, polyphenylene sulfone,polyalylate, graft polyphenylene ether, polyether ethyl ketone, andpolyether-imides; fluorinated resins, such as polytetrafluoroethylene,poly(fluorinated ethylene propylene),tetrafluoroethylene-perfluoroalkoxyethylene copolymers,perfluoroalkoxyethylene copolymers, ethylene-tetrafluoroethylenecopolymers, polyvinylidene fluoride, and fluorocarbon rubber; siliconeresins, such as silicone resins and silicone rubber; and othercompounds, such as methacrylic acid-styrene copolymers, polybutylene,and methyl methacrylate-butadiene-styrene copolymers.

On the other hand, the microcapsules 10 are fixed on the segmentelectrode 6 on the first substrate 2 and the periphery of thereof withan adhesive sheet 14. The microcapsules 10 on the second substrate 3 arefixed to the adhesive sheet 14; hence, many microcapsules 10 are heldand fixed on the first substrate 2. Examples of the material for theadhesive sheet 14 include thermoplastic resins and ultraviolet-curableresins in addition to thermosetting resins.

The entire display unit 4 is enclosed with the single protective film 5.The protective film 5 has a size such that the entire display unit 4 isenclosed with the protective film 5 and has, for example, a rectangularshape. As shown in FIG. 1, the single protective film 5 is folded alongthe display unit 4 in a single direction (folding direction. In thisembodiment, the folding direction of the protective film 5 correspondsto the direction of the short side of the display unit 4.

Both ends 5 a and 5 b of the protective film 5 are overlapped and bondedto each other with a first adhesive 18 to a unitary folded seal 20. Thefolded seal 20 extends along the long side of the display unit 4. Theoverlap width W is designed to range from half the short-side length Lto the short-side length L of the display unit 4. In the case where theoverlap width W is set to be a length corresponding to the short-sidelength L of the display unit 4, the size of the protective film 5 andthe position where the protective film 5 is folded are easily set, thusfacilitating the production. Furthermore, the widest overlap width W canbe achieved within the allowable range to further improve moistureresistance, thus resulting in the seal with higher airtightness.

In this way, the folded seal 20 is disposed at the backside of thedisplay unit 4 and thus does not cause obstruction to the visualidentification of an image made by a viewer who looks at the image fromthe side of the surface of the display unit 4, i.e., from the secondsubstrate 3 side, functioning as the display surface.

In the protective film 5, the folded-seal 20 side is defined as abackside 5A, and a side opposite the backside 5A with the display unit 4provided therebetween is defined as a front 5B. As shown in FIG. 2, thefront 5B and the backside 5A of the protective film 5 are bonded to eachother with a second adhesive (not shown) at both sides of the long sideof the display unit 4 to form side seals 26 and 26. That is, the bothends of the long side of the display unit 4 are sealed with the sideseals 26 and 26.

The folded seal 20 and the side seals 26 and 26 are formed by weldingusing laser irradiation or ultrasonic treatment. After cooling andsolidification, the melted portions are integrally bonded to each otherto form the folded seal 20 and the side seals 26 and 26.

The protective film 5 has a two-layer structure of a resin layercomposed of a polymeric material and a barrier layer composed of aninorganic material. When the pair of the substrates 2 and 3 is enclosedwith the protective film 5, the protective film 5 is disposed in such amanner that the barrier layer faces the substrates. When the protectivefilm 5 is disposed in such a manner that the barrier layer faces theoutside, water can penetrate the inside through a defective portion ofthe barrier layer. Since the protective film 5 is disposed in such amanner that the barrier layer faces the substrates, the outer resinlayer can prevent the penetration of water and the like from the outsideeven when a defective portion occurs in the barrier layer. The resinlayer has high water-barrier properties but often has water absorbency.When the protective film 5 is disposed in such a manner that the resinlayer faces the substrates, water absorbed in the resin layer canpermeate the inside the display unit 4. The protective film 5 isdisposed in such a manner that the resin layer faces the outside,thereby preventing the direct penetration of water and the like from theresin layer into the display unit 4.

Examples of the material suitable for the barrier layer includeinorganic materials, such as silicon oxide, silicon nitride, aluminumoxide, and titanium oxide. Alternatively, metal foil, such as aluminumfoil, copper foil, or Kovar foil is suitably used.

Examples of the material suitable for the resin layer includepolyesters, such as polyethylene terephthalate (PET), polyethylene (PE),polypropylene (PP), polyether sulfone (PES), and polyethylenenaphthalate (PEN); and resins such as polycarbonate (PC). Alternatively,metal foil, such as aluminum foil, copper foil, or Kovar foil, or alaminate of a thin metal film and a resin film is suitably used.

The first adhesive 18 is applied to one of the inner and outer faces ofone end of the protective film 5 in the folding direction within therange such that the folded seal 20 can be formed. Sealing is performedby bonding the one end to the other end with the first adhesive 18provided therebetween. In this embodiment, the end 5 b is laminated onthe end 5 a of the protective film 5 in the folding direction. Thus, thefirst adhesive 18 is applied to the outer face of the end 5 a.Alternatively, the first adhesive 18 may be applied to the inner face ofthe end 5 b. In any case, the first adhesive 18 is applied in such amanner that the ends 5 a and 5 b are surely bonded to each other.

The second adhesive is applied to predetermined areas of the both endsof the protective film 5 along short sides 4 b of the display unit 4 tobe enclosed. That is, the second adhesive is applied to the areascorresponding to the side seals 26 and 26 described above. The ends ofthe protective film 5, i.e., the ends of the front 5B and the backside5A, in the direction of the long side of the display unit 4 are bondedto each other along the short sides 4 b of the display unit 4.

The entire display unit 4 is enclosed with the single protective film 5using the first adhesive 18 and the second adhesive. Examples of thematerial for the first adhesive 18 and the second adhesive includeresins, such as epoxy resins, silicone resins, and acrylic resins; and amixture of an inorganic filler, such as silicon nitride, and one ofthese resins.

Method for Producing Electrophoretic Display

A method for producing the above-described electrophoretic display willbe described below with reference to FIGS. 1 to 4.

A method for forming the display unit 4 will be simply described.

The rectangular first substrate 2 composed of a polyimide is prepared.The segment electrode 6 having a predetermined shape is formed in thedisplay region A on the first substrate 2 by a semiadditive process orthe like. According to need, a flexible driving-circuit substrate (notshown) is connected to one end of the first substrate 2 in the directionof the long side.

The rectangular second substrate 3 composed of transparent polyethyleneterephthalate (PET) is prepared. The common electrode 7 composed of ITOis formed by evaporation on the entire inner face of the secondsubstrate 3.

Many microcapsules 10 are fixed by printing or the like on the surfaceof the common electrode 7 on the second substrate 3 with the binder 12to form the electrophoretic layer 13. The adhesive sheet 14 is bondedonto the segment electrode 6 and the periphery of the segment electrode6 on the first substrate 2. In this way, the second substrate 3 isdisposed so as to be opposite the first substrate 2 having the adhesivesheet 14. The electrophoretic layer 13 side of the second substrate 3 ispressed against the segment electrode 6 side of the first substrate 2,and then the substrates 2 and 3 are laminated. In this case, the firstsubstrate 2 and the second substrate 3 opposite each other aretransferred into a vacuum laminator 19 (see FIG. 4) and are bonded toeach other with the vacuum laminator 19.

Vacuum Laminator

As shown in FIG. 4, the vacuum laminator 19 includes a press unit 23having an upper holder 21 provided with a heater and a lower holder 22provided with a heater, the lower holder 22 being opposite the upperholder 21; and a vacuum unit connected to the press unit 23.

The upper holder 21 includes cushioning 25 composed of silicone rubberor the like, the cushioning 25 being disposed at the inner side of theupper holder 21. The lower holder 22 has a balloon shape which can beinflated with air and which is composed of silicone rubber or the like.The lower holder 22 is inflated with air. The lower holder 22 is broughtinto close contact with the first substrate 2 so as to fit in the shapeof the first substrate 2 by adjusting the degree of swelling, therebyuniformly pressurizing the first substrate 2. Hence, the substrates 2and 3 are appropriately and uniformly pressurized with the cushioning 25and the lower holder 22 without applying an excessive load to themicrocapsules 10.

To laminate the substrates 2 and 3 with the vacuum laminator 19, first,the vacuum laminator 19 in which the first substrate 2 and the secondsubstrate 3 are placed is evacuated with the vacuum unit. The lowerholder 22 is inflated by blowing air with the evacuation of the vacuumlaminator 19 to elastically deform the cushioning 25 and the lowerholder 22 along the external contour of the display unit 4, thusuniformly pressurizing the substrates 2 and 3. Simultaneously, thesubstrates 2 and 3 are heated to, for example, about 100° C. with theheaters attached to the upper holder 21 and the lower holder 22 to curethe adhesive sheet 14 adhering to the segment electrode 6 on the firstsubstrate 2 and the periphery of segment electrode 6, thereby laminatingthe first substrate 2 and the second substrate 3.

The pair of the first substrate 2 and the second substrate 3 oppositeeach other are disposed between the upper holder 21 and the lower holder22 and then subjected to thermal compression bonding to form therectangular display unit 4 holding the microcapsules 10 between thesubstrates 2 and 3.

The singe rectangular protective film 5 that is in the form of arectangle is prepared. The first adhesive 18 is applied to an areacorresponding to the folded seal 20 of the end 5 a in the foldingdirection (the outer side of the protective film 5). The second adhesiveis applied to areas corresponding to the side seals 26 and 26 (the innerface of the protective film 5) of both ends in the directionperpendicular to the folding direction of the protective film 5. Thedisplay unit 4 is placed at the substantially middle portion of theinner face of the protective film 5 in such a manner that the directionof the short side of the display unit 4 corresponds to the foldingdirection of the protective film 5.

As shown in FIG. 3, the side of the end 5 a to which the first adhesive18 is applied is folded toward the backside of the display unit 4 insuch a manner that the folding position corresponds to the long side 4 aof the display unit 4. Subsequently, the side of the end 5 b without anyadhesive is folded toward the backside of the display unit 4 to fix theend 5 a to the end 5 b overlapping the end 5 a with the first adhesive18. Thereby, the folded seal 20 is formed at the backside of the displayunit 4 and disposed along the direction of the long side of the displayunit 4.

Next, the side seals 26 and 26 are formed with the vacuum laminator 19.

The display unit 4 wrapped with the protective film 5 is transferredinto the vacuum laminator 19 shown in FIG. 4. The display unit 4 isplaced in the press unit 23 of the vacuum laminator 19. The press unit23 is evacuated with the vacuum unit.

The lower holder 22 is inflated by blowing air with the evacuation ofthe press unit 23 to deform the cushioning 25 and the lower holder 22along the external contour of the display unit 4. As a result, the endsof openings of the protective film 5 that is in the form of asubstantially rectangular cylinder extends along the direction of theshort side of the display unit 4. Thus, the ends of the front 5B overlapthe respective ends of the backside 5A. The overlapping ends areintegrally bonded to each other with the second adhesive. Thereby, asshown in FIG. 2, the side seals 26 and 26 are formed at both outer sidesin the direction of the long side of the display unit 4 to seal theentire display unit 4 with the single protective film 5.

In this embodiment, the display unit 4 is enclosed with the singleprotective film 5, thus reducing the sealing region that may undergo thepenetration of water and the like. This reduces the number of paths forthe penetration of water and the like, thus improving the moistureresistance at the periphery of the electrophoretic display 1. The foldedseal 20 is disposed along the face of the substrate of the display unit4; hence, the seal does not protrude from the perimeter of the displayunit 4, resulting in the miniaturization of the display unit 4.Furthermore, the overlap width W of the folded seal 20 can besufficiently ensured, thus inhibiting the penetration of water and thelike over long periods of time. This prevents the degradation of themicrocapsules 10 in the display unit 4 to impart excellent moistureresistance to the display unit 4. Hence, the degradation of the displayperformance of the display unit 4 is prevented to markedly improve thedurability and lifetime of the display unit 4, thus maintaining asatisfactory quality of the electrophoretic display 1.

Furthermore, the folded seal 20 is disposed at the backside of thedisplay unit 4, thus providing a satisfactory image for a viewer wholooks at the image from the front side. Hence, the viewer can visuallyidentify a clear image with comfortable feeling. Moreover, the foldedseal 20 is disposed at the backside of the display unit 4; hence, theaesthetics of the product is not degraded.

Furthermore, the folded seal 20 is formed along the long side of therectangular display unit 4, thus facilitating the production than thecase where the folded seal 20 is formed along the short side. The sideseals 26 and 26 are disposed along the short side 4 b of the displayunit 4, thus reducing the sealing length of the side seals 26 and 26.

Therefore, the number of paths for the penetration of water and the likefrom the outside is reduced to prevent the degradation of moistureresistance. Thus, the degradation of the microcapsules 10 can beinhibited, thereby maintaining a satisfactory quality of the displayunit 4.

The side seals 26 and 26 are disposed so as to protrude outward fromboth sides in the direction of the long side of the display unit 4 toform a known sealing structure. Thus, a driving-circuit substrate andthe like can also be connected as in the known art. For example, one ofthe side seals 26 and 26 can be connected to a flexible driving-circuitsubstrate.

The overlap width W of the folded seal 20 is set to a widthcorresponding to the short-side length L of the display unit 4; hence,the penetration of water and the like through the folded seal 20 can besufficiently inhibited, thus further improving the moisture resistanceof the folded seal 20 and surely preventing a degradation in displayperformance due to the penetration of water and the like. Therefore, thereliability of the product can be ensured.

Electronic Apparatus

An electronic apparatus of the invention will be described below. Theelectronic apparatus of the invention includes the above-describedelectrophoretic display.

Examples of the electronic apparatus including the electrophoreticdisplay will be described below.

Wrist Watch

An example in which the electrophoretic display is applied to a displayportion of a wrist watch will be described below. FIG. 5 is a schematicperspective view showing the structure of a wrist watch 50. As shown inFIG. 5, the wrist watch 50 includes a display portion 56 that displays atime, a watch housing 52 as a frame of the display portion 56, and awatch band 54 attached to the watch housing 52. In the wrist watch 50according to this embodiment, the display portion 56 of the watch iscurved so as to wind around an arm of a user of the wrist watch 50.

Mobile Phone

An example in which the electrophoretic display is applied to a displayportion of a mobile phone will be described below. FIG. 6 is aperspective view showing the structure of a mobile phone 90. As shown inFIG. 6, the mobile phone 90 includes a plurality of operation buttons91, an ear piece 92, a mouthpiece 93, and a display portion 94.

Electronic Paper

An example in which the electrophoretic display is applied to a displayportion of electronic paper will be described below. FIG. 7 is aperspective view showing the structure of the electronic paper 110. Theelectronic paper 110 includes a main body 111 formed of a rewritablesheet having a texture and flexibility similar to paper and a displayunit having a display portion 114.

The electronic apparatus according to this embodiment includes theelectrophoretic display 1 which has satisfactory moisture resistance andprevents the penetration of water and the like in air into the displayunit 4. Thus, a high-quality, high-reliability electronic apparatus canbe provided.

Examples of the electronic apparatus include electronic notebooks,personal computers, IC cards having fingerprint detectors, electronicbooks, viewfinder type or direct viewing type video tape recorders, carnavigation systems, pagers, personal digital assistants, desktopelectronic calculators, word processors, workstations, videophones, POSterminals, and devices having touch panels in addition to the wristwatch, the mobile phone, and the electronic paper, which include theelectrophoretic displays 1 as display portions.

The technical range of the invention is not limited to theabove-described embodiments. Various modifications may be made withoutdeparting from the gist of the invention.

For example, in the above-described embodiment, the examples includingthe microcapsules 10 have been described. Alternatively, anelectrophoretic dispersion layer containing the electrophoreticparticles 8 dispersed in the liquid-phase dispersion medium 9 may bedisposed between the pair of the substrates 2 and 3.

Furthermore, the adhesive sheet 14 for bonding the substrates 2 and 3 isnot disposed on the segment electrode 6 but may be disposed on themicrocapsules 10.

1. An electrophoretic device comprising: an electro-optical panelincluding an electrophoretic layer having an electrophoretic dispersioncontaining electrophoretic particles dispersed in a liquid-phasedisperse medium, wherein the electro-optical panel is enclosed with asingle protective film folded, and a first portion of the protectivefilm is bonded to a second portion of the protective film at a firstbonding portion.
 2. The electrophoretic device according to claim 1,wherein the electro-optical panel is enclosed so as to be disposedbetween the first bonding portion and a third portion of the protectivefilm.
 3. The electrophoretic device according to claim 1, wherein a mainsurface of the electro-optical panel is enclosed so as to be disposedbetween the first bonding portion a third portion of the protectivefilm, and the main surface of the electro-optical panel is covered withthe third portion.
 4. The electrophoretic device according to claim 1,wherein a fourth portion of the protective film is bonded to a fifthportion of the protective film at a second bonding portion, and theelectro-optical panel is enclosed in such a manner that the firstbonding portion is opposite the second bonding portion with theelectro-optical panel provided therebetween.
 5. The electrophoreticdevice according to claim 4, wherein the electro-optical panel is in theform of a rectangle, the rectangle has a first short side; a secondshort side opposite the first short side; a first long side intersectingwith the first short side and the second short side and being longerthan the first short side and the second short side; and a second longside intersecting with the first short side and the second short sideand being opposite the first long side, and the electro-optical panel isenclosed in such a manner that the first short side and the second shortside are disposed between the first bonding portion and the secondbonding portion.
 6. The electrophoretic device according to claim 4,wherein the electro-optical panel is in the form of a rectangle, therectangle has a first short side; a second short side opposite the firstshort side; a first long side intersecting with the first short side andthe second short side and being longer than the first short side and thesecond short side; and a second long side intersecting with the firstshort side and the second short side and being opposite the first longside, both of the first portion and the second portion protrude outwardfrom the first short side of the electro-optical panel, and both of thefourth portion and the fifth portion protrude outward from the secondshort side.
 7. The electrophoretic device according to claim 1, whereinthe electro-optical panel is in the form of a rectangle, the rectanglehas a first short side; a second short side opposite the first shortside; a first long side intersecting with the first short side and thesecond short side and being longer than the first short side and thesecond short side; and a second long side intersecting with the firstshort side and the second short side and being opposite the first longside, and the electro-optical panel includes a driving circuit disposedalong at least one of the first long side and the second long side. 8.The electrophoretic device according to claim 7, wherein theelectro-optical panel includes a plurality of terminals for electricallyconnecting the electro-optical panel and the outside of theelectro-optical panel, and the plurality of the terminals are disposedalong at least one of the first short side and the second short side. 9.An electrophoretic display comprising: a display portion including anelectrophoretic layer having an electrophoretic dispersion containingelectrophoretic particles dispersed in a liquid-phase disperse medium,the electrophoretic layer being disposed between a pair of substrates,wherein the display portion is enclosed with a single protective filmfolded, and ends of the protective film in the folding direction areoverlapped and fixed at one of the front side and the back side of thedisplay portion to form a seal.
 10. The electrophoretic displayaccording to claim 9, wherein the seal is disposed at the back side ofthe display portion.
 11. The electrophoretic display according to claim10, wherein the display portion is in the form of a rectangle, thefolding direction of the protective film corresponds to the direction ofthe short side of the display portion, and the seal is thus disposedalong the direction of the long side of the display portion.
 12. Theelectrophoretic display according to claim 9, wherein the displayportion includes a driving circuit disposed along at least one of thefirst long side and the second long side.
 13. The electrophoreticdisplay according to claim 9, wherein the display portion includes aplurality of terminals for electrically connecting the display portionto the outside of the display portion, and the plurality of theterminals are disposed along at least one of the first short side andthe second short side.
 14. The electrophoretic display according toclaim 9, wherein the overlap width of the ends in the folding directionat the seal ranges from half the length of the short side to the lengthof the short side of the display portion.
 15. An electronic apparatuscomprising: the electrophoretic display according to claim 1.